1. Field of the Invention
The present invention relates to a lamp having light emitting diodes as a lighting source, which is suitably used for a variety of automobile lamps, such as a stop lamp, a head lamp, a tail lamp, a turn signal lamp, a parking lamp, and the like, especially for a high mounted stop lamp.
2. Prior Art of the Invention
Heretofore there have been employed exclusively, as automobile lamps, those having a filament as a lighting source. Filament lamps have, however, many drawbacks, such as consuming a lot of electric power, generating great amounts of heat, readily snapping filaments, the lamp per se being large and heavy.
In order to overcome these problems, an idea has been proposed wherein instead of the filament lamp, light emitting diodes are adopted as the lighting source. The proposal may solve the above problems of the filament lamp, because light emitting diodes emit light using a lower voltage and current than those of a filament lamp, and also are small and light, and furthermore seldom include the problem of snapping a wire, thus realizing low electric power consumption, low heat generation, substantially no snapping so the lamp can be used semipermanently, small size, and light weight.
An individual light emitting diode, however, is very low in lighting power to be forwardly emitted because not only is the total lighting power per se rather low, but also it emits light in all directions. The light emitting diode, though being suited as a small indoor illuminator, is required to strengthen its forward lighting power, when it is used for a stop lamp of an automobile. The stop lamp should have such a strong forward lighting power that it is enough to call attention to succeeding vehicles to satisfy the provisions stipulated in D 5500 (automobile lamp) of Japanese Industrial Standard, FMVSS-108 (Federal Motor Vehicle Safety Standard No. 108), or like rules. In a stop lamp of a light emitting diode type already proposed, about 90 to 200 of resin-molded light emitting diodes, each of which includes a small light reflecting cap and a chip of a light emitting diode located thereon, are used and mounted on an insulating board in order to satisfy those standards concerning automobile or vehicle lamps. Those stop lamps are, however, costly, they require time consuming work both in individually molding the light emitting diodes and in assembling them on the insulating board which is accompanied with complicated wiring.